Viruses capable of causing cell transformation

# Which of the following viruses is NOT capable of causing cell transformation?
A. Retrovirus
B. Herpes virus
C. Hepatitis B virus
D. Human papilloma virus
E. Picorna virus

The correct answer is E. Picorna virus.

Picornavirus is an extremely small, ether-
resistant RNA virus which is not capable of
cell transformation. This virus can cause
several different disease conditions.

Diseases caused by Picornavirus include:
- Poliomyelitis
- Herpangina
- Aseptic meningitis
- Encephalomyocarditis
- Foot-and-mouth disease

Prognosis of a tooth

# Which of the following is the MOST critical factor determining the prognosis of a periodontally involved tooth?
A. Mobility of the tooth
B. Probing depth
C. Amount of attachment loss
D. Presence of furcation involvement

The correct answer is C. Amount of attachment loss.

The amount attachment loss determines
the prognosis of periodontally
Compromised teeth.

Teeth with severe attachment loss and
vertical mobility present a hopeless
prognosis and must be extracted to avoid
infection that may compromise other teeth.
The higher the quantity of attachment, the
better the prognosis.

Elevators are instruments designed to:

# Elevators are instruments that are designed to:
A. Engage the tooth coronal to the cementoenamel junction
B. Retract the crestal gingiva before forceps are used
C. Reflect a full thickness flap before forceps are used
D. Engage the tooth apical to the cementoenamel junction

Elevators are instruments used to elevate
the tooth out of its socket.

Elevators are designed to engage the root
portion of the tooth below the
cementoenamel junction.

Elevators are inserted into the periodontal
ligament space, create more room for tooth
movement, and help elevate the tooth out of its socket.

Most undesirable property of sodium hypochlorite

# Which of the following is the most UNDESIRABLE property of sodium hypochlorite?
A. Tendency to bleach tooth structure
B. Reaction with chelating agents
C. Smell
D. Corrosiveness to endodontic files
E. Toxicity to vital tissue

The correct answer is E. Toxicity to vital tissue.

Sodium hypochlorite in undiluted or
excessive amounts is toxic to vital tissues
and can cause periapical tissue damage
and pain.
Sodium hypochlorite is a good disinfectant
that is used in dentistry as an endodontic
canal irrigant at a diluted concentrations.
Sodium hypochlorite is used often used to
disinfect gutta percha points prior to
placement and obturation of the canal.